Open pore ceramic bodies, as for example have been disclosed in U.S. Pat. No. 3,090,094, serve, for example, as heat-resistant filters for molten metals, as heat-resistant catalyst carriers and for a plurality of other applications that make use of the fine pore structure of the ceramic body.
These types of open pore ceramic bodies are usually obtained by immersing an open pore matrix body made of a suitable, thermically decomposable or volatilizable material into a fluid ceramic mass that penetrates into the open pore system of the matrix body, and first, essentially, filling this latter. Suited as fluid ceramic masses are pastes made of finely-distributed ceramic powders with the addition of binding agents. After as complete as possible wetting of the contacting surfaces of the matrix body pores, the matrix body is removed from the ceramic mass and is rid of the excess of ceramic mass by expressing it, or by a comparable process. In doing this, a certain amount of the ceramic mass remains behind inside the matrix body, which covers the contacting surfaces of the pores with a relatively thin layer and, otherwise, leaves open the inside of the pores. Next, the ceramic mass is hardened, for example by drying and subsequent heating, possibly up to the point of vitrifying the ceramic particles together into an essentially one-piece body. In doing this, the matrix body is thermically volatilized or decomposed, with the product of decomposition escaping in the form of a gas. The ceramic body thereby remaining behind and consisting of the hardened, open pore ceramic mass, is furnished for the usages mentioned.
Resulting with this process for the production of an open pore ceramic body is an irregular ceramic skeleton prescribed essentially by the pore and cell wall structure of the matrix body, said skeleton forming the ceramic body. The possible supply and passageways for any arbitrary fluids and that are practically no longer capable of being influenced afterwards.
The invention starts with the recognition that it is desirable, to be able to plan defined supply channels for fluid substances, which would essentially expand the possible applications of the ceramic body. A ceramic body with defined supply channels would, for example, permit introducing certain reactants into the pore system in targetted fashion and there permit reaction partners flowing and/or diffusing through the pore system to react.
Now, however, because of the fineness and high degree of brittleness of the ceramic skeleton forming the ceramic body, it is possible to lay out these types of supply channels later only with some disadvantages. In the attempt to establish these types of supply channels, possibly by drilling or similar processes, in the finished ceramic body, occurring is considerable destruction of the pore system, blockage of pores by drilling dust, broken pieces, or similar, and possibly even extensive destruction of the ceramic body.
Therefore, the task for the invention is to obtain a process for producing open pore ceramic bodies of the initially mentioned art that are provided with defined supply channels, without the disadvantages described.
A further task for the invention consists of making ready an open pore matrix body suitable for the production of this type of open pore ceramic body. Furthermore, also a task for the invention is to obtain an open pore ceramic body that is provided with supply channels without any noteworthy disturbance of its pore system. Additionally, also the task for the invention is to give possibilities for application for a ceramic body of this type.